The present invention relates to the field of actuating drives. More specifically it relates to actuating drives for lifting motor vehicle windows.
An actuating drive of this general type is disclosed in unpublished European Patent Application No. 88116226.7. That actuating drive includes two axially-joined, cup-shaped housings: a gear housing and a cable pulley housing. The gear housing houses a worm gear turned by a worm shaft, which is in turn powered by a driving motor. The cable pulley housing houses a pulley for a cable attached to the motor vehicle window mechanism. The gear housing is sealed by a separate housing cover. Two seal mechanisms are used to seal the interior of the housings. First, a flat seal is assembled between the housing cover and the outer wall of the cable pulley housing. Second, an O-ring seal is assembled between the housing cover and the worm gear. Another O-ring is mounted as an axle seal between the worm gear and its axle.
Although the previously-disclosed actuating drive works quite well and offers numerous advantages, it suffers from several drawbacks. Several of these drawbacks stem from the use of a separate housing cover. The cost of the housing cover increases the cost of the actuating drive, as does the seal required between the housing cover and the worm gear. The use of the housing cover also adds a step to the assembly process, increasing assembly cost. The housing cover adds axial thickness to the actuating drive. Other drawbacks stem from the seals. The assembly process is complicated by the need to properly position the seal with respect to the other actuating drive components during the assembly process. Further, sealing relative to the worm gear can be unreliable with long time periods between actuating drive operation and with extreme temperatures.
Thus, it is evident that there is a need for improved actuating drives which eliminate the housing cover, simplify assembly of the seals with other actuating drive components, and provide reliable sealing over wide temperature ranges and with long time periods between actuating drive operation.